65 votes
Accepted

What is a soft fork? What is a hard fork? What are their differences?

What is a Project Fork? A fork in software development refers to the event of an independent project spinning off from a software project. Such forks sometimes occur in the opensource sphere, when ...
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  • 64.5k
62 votes
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What are Channel Factories and how do they work?

What are Channel Factories? In short, Channel Factories are payment channels that can be used to create more payment channels. That sounds weird, but it's really pretty simple: In a regular payment ...
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43 votes

What is meant by Bitcoin dust?

The definition of dust is client-specific and not a network rule. Bitcoin Core considers a transaction output to be dust, when its value is lower than the cost of spending it at the dustRelayFee rate. ...
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  • 64.5k
32 votes

What is a soft fork? What is a hard fork? What are their differences?

Softforks are forwards-compatible Old nodes will accept blocks created by new nodes. With a softfork, only miners will have to upgrade, or else they will end up on the losing fork. Users and ...
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19 votes
Accepted

Why is coinbase mentioned in a BIP?

The coinbase mentioned in BIP34 is not the company; it is referring to the first transaction in a Bitcoin block (which is special as it is allowed to bring new currency into circulation). Coinbase-the-...
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18 votes

What is a soft fork? What is a hard fork? What are their differences?

I found the best exact definition in the First three paragraphs here: gavinandresen / BitcoinVersioning We recently rolled out two changes to the Bitcoin block acceptance rules (BIP16 and BIP30); ...
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  • 281
18 votes
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What is the minRelayTxFee?

The minRelayTxFee specifies a feerate acting as a lower bound for a node's mempool. A node will not admit unconfirmed transactions below that feerate to its mempool and thus will not relay them to its ...
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  • 64.5k
17 votes

What is a mBTC?

m is the symbol for the metric prefix milli which indicates a unit to be one thousandth of its base unit. A millibitcoin therefore is 0.001 BTC or 1/1000 BTC.
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  • 64.5k
16 votes

What is the difference between a miner and a full node?

A 'full node' is a participant on the network that has independently validated the complete copy of the blockchain, and thus has verified all transactions since the beginning. This requires about ...
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13 votes

What is meant by transaction 'pinning'?

Transaction pinning happens when: I broadcast a transaction that signals opt-in RBF the transaction does not get confirmed because the feerate is too low someone else broadcasts a new (child) ...
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  • 900
12 votes

What is meant by Bitcoin dust?

To understand 'dust' you must understand a few things: Firstly, a UTXO is an unspent transaction output. This is essentially a piece of bitcoin somewhere on the blockchain that is unspent. To create ...
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12 votes

Replace-by-Fee vs Child-pays-for-Parent?

Replace-by-fee means transactions spending the same coin to the same addresses are not considered double-spends by the network and are still relayed, as long as they pay a higher fee than the ...
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  • 971
12 votes
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What is the difference between "native segwit" and "bech32"?

TL;DR: Native segwit refers to segwit outputs without P2SH-wrapper. Bech32 is the address format used to represent native segwit-v0 locking scripts. Wrapped segwit vs native segwit When segwit ...
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  • 64.5k
11 votes

What is a nonce?

Nonce is a 32 bit arbitrary random number that is typically used once. In Bitcoin's mining process, the goal is to find a hash below a target number which is calculated based on the difficulty. Proof ...
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10 votes
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What does "Activating Best Chain" mean?

Bitcoin Core maintains two databases: The block index The chain state (or UTXO set) The first one just contains a list of all blocks we know about, valid and invalid. It contains all forks we have ...
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10 votes

Is it correct to say that Bitcoin has a virtual machine in the same way as Ethereum does?

"Virtual machine" in this context is really just a fancy word for bytecode interpreter. Bitcoin's script language is certainly far simpler than Ethereum's EVM, and its functionalities are in ...
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9 votes

What are tainted coins exactly?

The term "Tainted Coins" is often misinterpreted as a measure of provenance. That's understandable considering the traditional definition of the word "tainted" coupled with the reality that many ...
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  • 101
9 votes
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What does "lock time" mean?

A specified locktime indicates that the transaction is only valid after a given blockheight. Since the locktime field indicated is 419382 and currently the latest blockheight as of 12th July 2016 1108 ...
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  • 2,378
8 votes

What the difference between old segwit (3) and new segwit address (bc)?

The difference lies in the encoding and the underlying representation in the transaction data stored on the blockchain. The 3-segwit addresses are known as P2SH-P2WPKH or P2SH-P2WSH. This stands for ...
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  • 16.5k
8 votes
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Redeem script. script hash, witness script and witness program

The scriptPubKey is the script as it is placed in the transaction output. The redeemScript (P2SH only) is the script pushed as the last scriptSig item. In P2SH scripts, the scriptPubKey is equal to ...
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7 votes

What are checkpoints?

Update on this as of time of writing, just to clarify more specifically upon the other answer: dependence on checkpoints in the security model has been significantly reduced, they are only used in one ...
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7 votes
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What is a block?

There are a lot of questions on the Bitcoin SE about blocks, but remarkably I couldn't find any that explicitly lay out what a block is. A blocks has two things: A block header and a list of ...
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  • 13.7k
7 votes
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What is the meaning of the term "full-node"?

Fully validating nodes ("full nodes") are clients that have validated the whole blockchain self-sufficiently and enforce all of the rules of Bitcoin on any data they receive. Therefore, they cannot be ...
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  • 64.5k
7 votes
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What is the difference between on-chain scaling and off-chain scaling?

Note, I use scaling, capacity, and scalability as follows: Scaling: Growing the network's utility in any fashion. Capacity: The number of transactions that can be processed on the network. Scalability:...
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  • 64.5k
7 votes

Are BTC and Bitcoin Core the same?

Kind of. People who call Bitcoin "Bitcoin Core" are referring to Bitcoin. They will also use the name "Bitcoin Legacy". but calling Bitcoin "Bitcoin Core" or "Bitcoin Legacy" is misleading. Bitcoin ...
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  • 62.4k
7 votes
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What is the difference between blocksonly and block-relay-only in Bitcoin Core?

While both of these disable transaction relay, they are conceptually used for different purposes: Block-relay-only connections (see this post for more details) are hard-to-detect connections with the ...
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  • 421
7 votes

What does TLV stand for?

TLV stands for type-length-value. It's an encoding scheme used when protocols allow for optional elements in their messages. The type is a label telling you what field you're looking at, the length ...
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  • 64.5k
6 votes

What does the blockchain represent?

The blockchain is the complete transactional history of Bitcoin. It collects every transaction performed in blocks which each are linked to their predecessor block. By parsing the complete blockchain,...
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  • 64.5k
6 votes

What is the minRelayTxFee?

'minRelayTxFee' is the node's minimum reward (BTC/KB) for a transaction "transmission" (relay). In the p2p network there could be a node (A) with a minRelayTxFee setted at 0,0001 and a node (B) with a ...
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6 votes
Accepted

What the difference between old segwit (3) and new segwit address (bc)?

There's no big difference for users between the two. The fee is lower while using native Segwit address (bech32), and the address format differs. Let's look at the motivations of bech32 address ...
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